Chipmunks are genus which contains 23 species, and which almost all are found in North America. Their closest family member are the genus Eutamis, which consists on one species of the Siberian chipmunk.

The least chipmunk is the smallest species of chipmunk and the most widespread in North America. This species is from 6 to 10 inches in length, and weighs from 1 to 2.5 ounces. The body is gray to reddish brown on the sides, grayish white on the under side.

The back is marked with five dark brown or black stripes separated by four white or cream colored stripes. All of the back strips run from the nape of the neck to the base of the tail. Two light and two dark strips run from the tip of the nose to the ears marking each side of the face.

The tail is bushy, orange-brown in color and is about three and a half inch to four and a half inch in length.

There are four toes on each forefeet and five toes on the hindfeet. Females have eight teats.

Less arboreal than other chipmunks, least chipmunks are commonly found in sagebrush habitats and coniferous woodland, along rivers, but they are also found in alpine meadows, and on the edges of the northern tundra.

Least chipmunks are found through most of the western United States from northern New Mexico and western North and South Dakota to eastern California, Oregon and Washington, and throughout much of southern and western Canada from Yukon and southeastern British Columbia to central Ontario, and into the Upper Peninsula of Michigan and neighboring parts of Wisconsin and Minnesota.